Preparation of hydrazine hydrate



United States Patent 3,189,411 PREPARATION (El HYDRAZTNE HYDRATE Heinrich Kohnen, Rudolf hinndil, and Johst teinbrecht,

all of Leverknsen, Germany, assignors to Farhenfahrilten Bayer Ahtiengeseilsehat't, Leverlrnsen, Germany, a corporation of Germany No Drawing. Filed Ean. 23, 1962, Ser. No. 158 235 Claims priority, application Germany, Feb. 8,

9 Claims. (Cl. 23-490) This invention relates to a method of producing hydrazine hydrate, and more specifically is concerned with a method of preparing hydrazine hydrate from ketazines and hydrazones, particularly from dimethyl lietazine and acetone hydrazone.

It is known that in the production of hydrazine by the Raschig synthesis, solutions with a hydrazine content of only 1 to 2% are obtained. Furthermore, the yield is only in the region of 40 to 60%. It is also known that when bleaching liquor is reacted with ammonia and simple ketones, aqueous ketazine solutions are obtained in yields of more than 90% without the use of high pressures and temperatures, and that some of these solutions, for example in the case of dimethyl ketazine, have a lower boiling point than water and thus provide an extremely economical concentration of hydrazine in combined form. It is known that these ketazines can be split into hydrazine salt and ketone by acid hydrolysis. This hydrazine salt can, moreover, be worked up by various methods to hydrazine hydrate. Processes are also known, the object of which is to obviate this tedious and costly roundabout method by way of the salts and which permit the hydrate to be produced directly from ketazine solutions. However, all these proposals have basic defects which have prevented them from being carried out industrially.

Briefly described the method of the present invention comprises efiecting a decomposition of the dimethyl ketazine and the acetone hydrazone into acetone and hydraz ne by fractionating distillation at excess pressure and at a sump-temperature range between 100 to 250 C., said excess pressure being of about 1 to about 50 atmospheres.

If aqueous ketazine or hydrazone solutions are fractionated under high pressure and at high temperature, a splitting into ketone and hydrazine takes place hydrolytically, this permitting practically all the ketone to be removed at the top of the column. On the other hand, if the distillation is carried out under otherwise identical conditions at normal pressure, such a large excess of water is necessary to displace the hydrolytic equilibrium to effect the complete removal of the ketone that the process becomes completely uneconomical. Pressures of 1 to 50 and preferably of 1.5 to 20 atmospheres have proved to be suitable in practice.

Especially the decomposition of the ketazine and the hydrazone is effected in an aqueous medium containing about 19 to 25 percent of acetone and about 9 to 12 percent of hydrazine hydrate. Still more particularly the temperature range is between 130 to 210 C. and the excess pressure is from about to 15 atmospheres.

Illustrative examples of ketazines and hydrazones are dimethyl ketazine and acetone hydrazone, represented by the following formulae:

See

and

C=NNH2 The present invention provides a new and improved method of producing hydrazine hydrate in an economic manner, said method has the advantage of simplicity and avoids the necessity for using complicated apparatus techniques.

The following examples are given by way of illustrating and showing how the present invention can be carried into eiiect.

Example 1 Example 2 An aqueous solution of dimethyl-ketazine containing 9% hydrazine hydrate and 21.9% acetone is fractionated continuously in a column provided with filler bodies at a pressure of 4 atm. The run-in amounts to litres per hour. From the top of the column there have been withdrawn 18 litres per hour of a solution containing 91% acetone and 2.3% of hydrazine hydrate. The sumptemperature amounts to 145 C. The analytical result of the sump-running off shows 10.8% of hydrazine hydrate and 0.8% of acetone.

Example 3 An aqueous solution of dimethyl-ketazine containing 24.5% of acetone and 10.5% of hydrazine hydrate is fractionated continuously in a column having filler bodies at a pressure of 20 atm. and at a sump-temperature of 216 C. The run-in amounts to 125 litres per hour. At the top of the column there are withdrawn 30 litres per hour of a solution containing 96% of acetone and 1.5% of hydrazine hydrate. The composition of the sumprunning 011 is 0.1% of acetone and 12% of hydrazine hydrate.

Example 4 An aqueous solution of acetone hydrazone containing 10.4% of acetone and 11.1% of hydrazine hydrate is fractionated in a column with filler bodies at a pressure of 4 atm. and at a sump-temperature of 146 C. The run-in amounts to 100 litres per hour and the run oli to 10.8 litres per hour, containing 93.0% of acetone and 1.8% of hydrazine hydrate. The sump-running oft contains 0.3% of acetone and 12.1% of hydrazine hydrate.

Example 5 shows the following compounds: 0.1% of acetone and 14.3 of hydrazine hydrate.

a 'Wegclaim: V H

' pera-ture range is from 130 to 210 C. 3. Process according to claim 1 wherein said pressure 1 is from about 5 H515 atmospheres. I

tionally contains 21.3%

1.; A'process for the production of hydrazine hydrate which comprises decomposing a hydrazine compound selected from the group consisting "of dimethyl ketazine and acetone hydrazine in the form of an aqueous solution ":7 thereof by fractionally distilling such'a solution under a pressure of between 2 atmospheres and 50. atmospheres and at a sump temperature ranging between 120. and.

' 2. 7 Process according to claim 1 :wherein said sump tem- 4. Process according to claim 1 wherein said aqueous solution of fluid group 'memben additionally contains 5 about 19-25%. of acetone andabout 9. 12% of hydrazine hydrate. i

fdrazine hydrate by fractionally distilling such solution at a pressure of 4 atmospheresand ata sump temperature I 0f146 C. V V

'9. A process .forthe'production of hydrazine hydrate which comprises decomposing acetone hydrazoue in the 5. A process for the'productio'n of hydrazine hydrate I Qwhich comprisesdecomposing dimethylketazine in the form ofan aqueous solution thereofwhich solution addi ltionally contains 24.5% of acetone and 10.5% ofhydrazine hydrate by fractionally distilling such solution under a pressure of 9 atmospheres and at a sump tem-' perature of about 178 C..

6; A process for the production of hydrazine hydrate f which comprises decomposing Vdimethylketazine in the.

form of an aqueous solution thereof which solution addiacetone and 9% hydrazine I hydrate by fractionally distilling such solution at a pressure of 51 atmospheres, and at a sump temperature of 7 7. A process forfthe production of: hydrazine hydrate;

which comprises decomposing dimethylketazine in the 1 form of an aqueous solution thereof which solution additionally contains 24.5% of acetone and 10.5% of-hydrazine hydrate by fractionally distilling such solutionat.

a pressure of 20 atmospheres; and at a sump temperature of216C. r r ,7

3. A process for the'production of hydrazine hydrate which comprises decomposingacetone hydrazone in the 'form of an aqueous solution thereof which solution additionally contains 10.4% of acetone and 11.1% ofhyform of an aqueous solution lthereof which solutionu additionally contains 21.0% of acetone and 12.3% Of.' hydrazine hydrate by fractionally distilling such a solution at apressure of 20 atmospheres, and at a sump tem peratureof216 C. e r

References (Zited by the Examiner UNITED STATES PATENTS 3,028,219

- A. BRINDISI, Primary Examiner. 

1. A PROCESS FOR THE PRODUCTION OF HYDRAZINE HYDRATE WHICH COMPRISES DECOMPOSING A HYDRAZINE COMPOUND SELECTED FROM THE GROUP CONSISTING OF DIMETHYL KETAZINE AND ACETONE HYDRAZINE IN THE FORM OF A AQUEOUS SOLUTION THEREOF BY FRACTIONALLY DISTILLING SUCH A SOLUTION UNDER A PRESSURE OF BETWEEN 2 ATMOSPHERES AND 50 ATMOSPHERES AND AT A SUMP TEMPERATURE RANGING BETWEEN 120 AND 250*C. 